Automatic switch.



J. L. WOODBRIDGE.

AUTOMATIC SWITCH.

APPLICATION FILED DEC. 2, 1911.

1,125,242, Patented Jan.19,1915.

lIIVE/ITOR Ja 6h A. Wow/M2 6 2 er .L oak/tho JOSEPH 'WOOIDBRIDGE, OF PHILADELPHIA, PENNSYLVAITIA.

AUTOMATIC SWITCH.

Specification of Letters Patent.

Patented Jan MP, 1915,

Application filed December 2, 1911. Seria1No.663,542.

-b Gilt 710m it may concerniie it known that I, .losi-iru Lns'rnn Wir n- BRIDGE, a citizen of the United States, and a res dent of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Automatic Switches, of which the following is a specification.

My invention relates to switches which are designed to operate automatically to make and break the electrical connection between two circuits. and especially between two circuits, each of which is provided with a source of elcctromotive-force, whereof one mav be variable, such, for example, as the automatic switches which are used for malt ing connection between a dynamo driven at arying speed and a storage battery.

One of the principal objects of my invention is to provide means whereby the closing of such a switch is made to depend upon small di'l'i'erencc of potential between the voltage of the dynamo and that of the battery, the operation of the switch being at the same time positive and independent of ordinary variations of temperature, friction. etc. i

The general nature of my invention will be more clearly understood by'ret'erence to the following description taken in connection with the accompanying drawings, in which' Figure 1 is a view, partly in section and partly diagrammatic, of an electro magnetic switch involving features of my invention, including its circuit connections, and Fig. 2 is a plan view of the auxiliary magnet M, and its armatures.

Referring to Fig. 1, l is the frame and P the plunger oi an electro magnet provided with a line wire shunt winding 1 and a heavy wire series winding 2. battery 1) and a dvnamo G are shown, permanently con ected at one terminal of each by the conductor The opposite terminal of the dynamo is connected by conductor i to the fixed contact 5 of the automatic switch, while the opposite terminal of the battery is connected by conductor 6, and the series whirling '2 to the moving contact arm I oi the wvitch. Vihen the plunger P is in its low ion, as shown, the arm 7 is held ll-i ntact with contact 5 by means of a spi S, and rests against the stop 9.

may be suitably insulated from Th arm 7 A storage the stop and the spring in any convenient manner. The plunger P is provided at the bottom with a stem S which extends downward'through an opening in the armature A of a second elcctro magnet M. The stem S fits loosely in this opening in the armat ire A, and is provided with a cap or nut N, which will engage with the armature A d'iring the upward travel of the plunger. T he magnet M is of the ordinary horseshoe tvne, being provided with two soft iron cores C shown in plan in Fig. 2, connected at the bottom by an iron yoke Y. Each core is provided with a special pole piece Z extending to the left, and arranged to cooperate with a second armature A supported on the pivoted bar D. The bar D is pivoted at X to a support carried by the frame F, and as here shown has the form of a bell crank whose shorter arm V supports the moving member 7 of the switch by means of the pivot 10. The arm '7 may be suitably insulated from the arm W by means of an insulating bushing. The electro-magnet M is provided with two wind ings. One of these 11 is connected in series with the fine wire winding 1 ot' the main magnet. the two windings 11 and 1 being connected in shunt across the circuit 3-'lwith a resistance R in series therewith. Supported on the arm D, and insulated therefrom, is a contact piece 12 which, when the arm .is in the position shown at the left hand limit of its travel, makes contact with two points 13 and it connected to opposit:v sides of the resistance R, thus short-circuiting this resistance. When the arm D moves to the-right this contact is broken. The other winding 15, on the magnet M is con nected at one end by means of conductor 16 to the terminal of the resistance R, which is remote from conductor 4, and at the other end by means of conductor 17 to an in sulated contact 18 carried by the upper end of the plunger P. When the pl'linger l is in its lowest position, the vcontact 18 is separated from the arm 7, but as the plunger rises, and before the nut N on the stem 5 comes into contact with the armature A. the contact piece 18 makes contact with the arm 7. Under these latter conditions, the resistance R being short-circuited, the winding 15 is connected between conductor and the corresponding terminal of the battery B.

the circuit being completed by way of ii, 12,

13, 16, 15, 17, 18, 7, 2 and 6. A resistance 19 of high temperature coeflicient may be included in this circuit to limit the maximum current therein. The armature A is provided with adjustable stops 0 of nonmagnetic material to fix the air-gap between the armature A and the pole pieces Z when the arm D is at the right hand limit of its travel. The yoke Y is of smaller cross section than the armature A, and will, therefore, become saturated first.

The operation of the switch will then be a as follows: When the voltage of the generator G is below a certain limit which may be taken, for example, at one-half or one-third that of the battery B, the excitation of the shunt winding 1 will not be suflicient to overcome the weight of the plunger P, and the plunger will rest in its lowest position as shown, the bar 7 resting against the stop 9 out of contact with 5, and the contact piece 18 being out of contact with the bar 7. By reason of the tension of the spring 8 on the bar 7, the latter being fulcrumed at 9, there will be a downward pressure on the pivot 10, which will hold the bar D at the left hand limit of its travel, and the resistance R will be short-circuited by the contact piece 12.

As the voltage of the dynamo G increases, a point will be reached where the-effect of the winding 1 will be suflicient to overcome the weight of the plunger P, and the latter will be drawn upward, bringing the contact piece 18 into contact with the arm 7, thus energizing the winding 15. The windings 15 and 11 are so designed that they co5perate when the voltage of the dynamo G is below that of the battery B, but when the voltage of the dynamo G is above that of the-battery, the current in the winding 15 is reversed, and it opposes the winding 11. As the Voltage of the dynamo G increases a point is reached where the effect of winding 1 is suflicient not only to overcome the weight of the plunger P, but the tension of the spring 8. The plunger is, however, prevented from completing its travel, andclosing the contact between 7 and 5 by reason of the nut N, which comes in contact with the armature A, and the latter is held in position by the magnet M on account of the current in the cooperating coils lland 15. As the voltage of the dynamo G rises still farther, it will become equal to that of the'battery B, and finally exceed the latter by a small amount, thus reversing the direction of current in the coil 15. The design of the coils 11 and 15 is such that with a small excess of voltage in the dynamo G above that of the battery B, the effect of the .coil 15 will be equal and opposite to that of coil 11, the excitation of the magnet M will be reduced to zero and thearmature A will be released, allowing the plunger to continue its upward travel until contact is made between the bar 7 and the contact 5 of the switch, thus connecting the generator to the battery, and permitting a flow of current through the series winding 2 in the direotion to cooperate with the shunt winding 1. This will give additional force to the upward tendency of the plunger P, and the bar 7 having now come in contact with the fixed contact 5 the latter becomes the fulcruin'about which the bar 7 tends to turn with further upward motion of the plunger. This latter produces an upward thrust on the pivot 10, which will move the bar D about its pivot X, opening the short circuit at the contact points 13 and 14, thus introducing the resistance B into the circuit of the shunt windings 1 and 11. At the same time the armature A is brought close to the pole pieces Z, and by reason of the increased excitation of the magnet M which will be explained below, the armature A will be held against the pole pieces Z with a small air gap determined by the adjustment of the stops 0. The increased excitation of the magnet M is produced by the action of the coil 15 when the short-circuit, at the points 13 and 14, is opened. As soon as this occurs there will be a flow of current through the resistance R, and the windings 1 and 11. This current in the resistance R will produce a drop of voltage in that resistance, so that the terminal of that resistance, to which one end of the winding 15 is connected, will be at a lower potential than the other end of winding 15, which is connected by way of conductor 17, contact 18, bar 7 and contact 5 to conductor 1. The effect of coil 15 under these conditions will be to cotiperate with tion in the magnet M above referred to. The introduction of the resistance R into the circuit of the windings land 11 will somewhat weaken the eifect ofthese windings, but so long as the dynamo voltage is high enough to transmit current to the battery B in the charge direction, the effect of the series coil 2 added to that of the shunt coil 1 will be sufiicient to hold the switch closed. As soon, however, as the voltage of the dynamo G falls sufliciently to reduce the current in the series winding 2 nearly to zero, the excitation of the two coils 1 and 2 combined will not be sufiicient to hold the plunger in its upper position against the tension of the spring 8, and the switch will then open. The plunger will continue to fall until the armature A rests upon the magnet M, where it will be firmly held by the attraction of the latter magnet. As soon, however, as the armature A comes in contact with the pole pieces Z it will form a magnetic short circuit, and the lines of force, which were holding the armature A against these pole pieces, willnow be diverted through the armature A, and the armature A will be released, permitting the arm D to travel to the coil 11, and produce the increase of excitaleft in response to the tension of the spring 8, and the resulting downward thrust on the pivot 10. The resistance R- will again be short-circuited at the points 13 and 11, again strengthening the excitation of winding 1, and restoring the original conditions. the generator voltage should now rise again to a point where the current in the coil 15 is suitable in amount and direction to neutralize the efi'ect of coil 11, the armature A will again be released and permit the switch to close. If, however, the voltage of the dynamo G continues to decrease a point will be reached where the effect of the winding 1 will not be suiiicient to support the weight of the plunger P, and the latter will drop to its lowest position, opening the contact between 18 and 7, and thus preventing a continuous drain of current from the battery through the winding 15 when the generator is shut down.

It will be noted that before the effect of coil 1 is weakened by opening the short-circuit around resistance R, the contact between bar 7 and contact 5 must be made in order that the latter may be used as a fulcrum in imparting motion to the bar D. It is thus made certain that a flow of current is produced in the series winding 2 before the current in shunt winding 1 is reduced by the resistance R. It will also be noted that when the switch opens, before the short-circuit around the resistance R is restored, the armature A must come in contact with the pole pieces of magnet M, and be in a position to prevent the plunger from rising again upon increase of current in coil 1. The switch is thus made positive in its action, both upon closing and upon open- Ilaving described my invention what I claim and desire to secure by Letters Patent is 1. In combination in an electro-magnetic switch, a contact piece and a movable contact member, an electro-magnet for closing the contact between them, means dependent upon the closing of said contact and adapted to weaken the electro-magnet, electroresponsive restraining and releasing means for timing the closing of said contact, and means for holding the weakening means effective for weakening the magnet until the restraining means is effective to prevent closing the contact.

2. In combination in an electro-magnetic switch, a contact piece and a movable contact member an electro-magnet with its exciting coil for closing the contact betweenthem, means mechanically dependent upon the pressure at said contact for weakening the effect of the coil, electro-responsive restraining and releasing means for timing the closing of said contact, and means for holding the weakening means effective for weakening the effect of the coil until the restraining means is effective to prevent closing the contact.

3. In combination in an electro-magnetic switch, a contact piece and a movable contact member, a main electro-magnet with its exciting coil for closing the contact between them, means mechanically dependent upon the pressure at said contact for weakening the eiiect of the coil, an auxiliary electro-magnet and its armature adapted to prevent the closing of said contact, a releasing coil for said auxiliary magnet re sponsive to predetermined circuit conditions, and a second armature for the auxiliary magnet adapted to hold the weakening means effective to weaken the effect of the main magnet coil until released by the .magnetic short circuit produced by the first armature.

4. In combination, two electric circuits, a switch comprising a contact piece and a movable contact member adapted to make contact for connecting the two circuits, a main electro-magnet and its exciting coil for closing the switch contact, means mechanically dependent upon the contact pressure for weakening the effect of the coil, an auxiliary electro-magnet and its armature adapted to prevent the closing of said contact, and a releasing coil for said auxiliary magnet connected between the two electric circuits.

5. In combination, two electric circuits, a switch comprising a contact piece and a movable contact member adapted to make contact for connecting the two circuits, a main electro-magnet and its exciting coil for closing the switch-contact, means mechanicallv dependent upon the contact pressure for weakening the effect of the. coil, an auxiliary electro-magnet and its armature adapted to prevent the closing of said contact, a releasing coil for said auxiliary magnet connected between the two electric circuits. and a resistance of high temperature coefiicient in circuit with the releasing coil.

6. In combination, two electric-circuits, a switch comprising a contact piece and a movable contact member adapted to make contact for connecting the two circuits. a main electro-magnet and its exciting coil for closing the switch contact, means mechanically dependent upon the contact pressure f or weakening the effect of the coil, an auxiliary electro-magnet and its armature adapted to prevent the closing of said contact, a releasing coil for said auxiliary magnet connected between the two electric circuits, and means for automatically disconnecting the releasing coil, substantially as described.

7. In combination, in an electro-magnetic switch, a contact piece and a movable contact member, an electro-magnet with its exciting coil for closing the contact between them, means dependent upon the making of said contact for weakening the effect of the coil, restraining means for preventing the closing of said contact until predetermined circuit conditions obtain and then permitting said contact to be made, and means for holding the weakening means efiectiveto weaken the magnet coil until the restraining means is effective to prevent the closing of said contact.

8. In combination, two electric circuits, a switch comprising a contact piece and a movable contact member adapted to make contact for connecting the two circuits, a

main electro-magnet having an exciting coil and a moving part for closing the switch contact, means mechanically dependent upon the contact pressure for weakening the effect of the coil, an auxiliary electro-maguet and its armature adapted to restrain the motion of the moving part and thereby prevent the closing of the switch contact, a releasing coil for the auxiliary magnet connected between the two circuits and adapted to weaken said auxiliary magnet and permit the closing of the switchcontact upon a difference of potential between the circuits of a certain amount and polarity, and a second armature for the auxiliary magnet adapted to hold the weakening means effective to weaken the effect of the main magnet coil until said second armature is released by the magnetic short circuit ofthe first armature.

switch comprising two members adapted to make contact with each other to connect said circuits, a main electro-magnet having an exciting coil and a moving part adapted to close said contact, means mechanically dependent upon'the contact pressure for weakening the effect of the coil, means including an auxiliary electro-magnet adapted to restrain the moving part of the main magnet 4 to prevent the closing of the switch contact,

a releasing coil for the auxiliary magnet connected between the two circuits and adapted to modify its excitation to release the moving part of the main magnet to permit the closing of the switch contact upon a difference of potential between said circuits of a certain amount and polarity, a resistance of high temperature coefficient in circuit'with the releasing coil, and means for holding the weakening means effective to weaken the main magnet coil until the restraining means is effective to prevent the closing of the switch contact.

10. In combination in an electro-magnetic switch, two switch members adapted to make contact with each other, a main electro-magnet having an exciting coil and a moving part adapted to efi'ectsaid contact, a con- "tact'devi'ce for weakening the effect of the 35 exciting coil, said contact device being me- 9. In combination two electric circuits, a.

chanically actuated by one of the switch members in fulcruming on the other, restraining means adapted to prevent the moving part of the magnet from closing the switch contact until predetermined circuit conditions obtain and permit such closing when said conditions do obtain, and means for holding the weakening device in position to weaken the exciting coil until the restraining means is eif'ective to prevent the moving part from closing the switch.

11. In combination in an electric switch, an auxiliary contact lever mounted on a stationary fulcrum, a main contact member movably supported by said auxiliary contact lever, a main contact piece cooperating with the main contact member, a main electro-magnet having an exciting coil and a moving part arranged to cooperate with the main contact member to close the contact with the main contact piece and thereupon by reason of the fulcrum effect of said contact piece to transmit motion to the auxiliary contact lever, circuit connections from the exciting coil and contacts cooperating with the auxiliary contact lever whereby said motion of said lever weakens the effect of said exciting coil, an auxiliary restraining magnet and its armature adapted to restrain the motion of the moving part of the main magnet to prevent closing the main contact and to release said moving part to permit closing said contact in response to predetermined circuit conditions, and a second armature for the auxiliary magnet adapted to be held by said magnet and thereby keep the auxiliary contact lever in position to weaken the exciting coil until said second armature is released by the magnetic short circuit of the first armature.

an auxiliary contact lever mounted on a stationary fulcrum, a main contact member movably supported by said auxiliary contact lever, a main contact piece cooperating with the main contact member, a main electro-m-agnet having an exciting coil and a moving part arranged to cooperate with the main contact member to close the contact with the main contact piece and thereupon by reason of the fulcrum efiect of said contact piece to transmit motion to the auxiliary contact lever, circuit connections from the exciting coil and contacts cooperating with the auxiliary contact lever whereby said motion of said lever weakens the effect of said exciting coil, an auxiliary restraining magnet and its armature adapted to restrain the motion of the moving part of the main magnet to prevent closing the main contact, a releasing coil connected between the main contact member and the main contact piece and adapted to neutralize the magnetism of the auxiliary magnet to permit the closing of said main contact, and a I? 12. In combination in an electric switch second armature for the auxiliary magnet adapted to be held by said magnet and thereby keep the auxiliary contact lever in position to weaken the exciting coil until said second arn'iature is released by the magnetic short circuit of the first armature.

13. In combination, in an electric switch, a contact piece and a movable contact member, an electro-magnet for closing the contact between them, saidmagnet having a shunt winding and a series winding, and means dependent upon the mechanical contact pressure between the contacts for weakening the eliect of the shunt winding whereby said weakening is produced after a fiow of current is established in the series winding.

14. In combination, in an electric switch, a contact piece and a movable contact member, an electro-magnet for closing the contact between them, said magnet having a shunt winding and a series winding, a resistance in series with the shunt winding, means for short circuiting said resistance, and means mechanically dependent on the pressure at the contact for opening said short circuit whereby the effect of the shunt coil is weakened after a how of current is established in the series winding.

15. In combination in an electric switch a contact piece and a movable contact memher, a main electro-magnet for closing the contact between them, a restraining device including an auxiliary electro-magnet for preventing the closing of said contact, and a releasing coil for said electro-magnet connected between thecontact piece and the movable contact member and adapted upon a predetermined flow of current therethrough to permit the closing of said contact.

16. In combination in an electric switch a contact piece and a movable contact member, a main electro-magnet for' closing the contact between them, a restraining device including an auxiliary electro-magnet for preventing the closing of said contact, a releasing coil for said elcctro-magnet con nected between the contact piece and the movable contact member and adapted upon a predetermined flow of current therethrough to permit the closing of said contact, and means for automatically disconnecting the releasing coil, substantially as described.

17. In combination in an automatic switch, interconnected main and auxiliary contact arms, whereoi the former is movably supported by the latter, a fixed contact adapted to operate as a fulcrum for the main contact arm in moving the auxiliary arm, a main electro-magnet having a moving memher for operating the main contact arm in respect to the fixed contact and having an exciting winding, an auxiliary magnet adapted to restrain and release the movement both of the moving member of the main magnet and of the auxiliary arm, a coil on the auxiliary magnet for releasing the moving member of the main magnet, and means controlled by the auxiliary arm for modifying the excitation of the main electro-inagnet.

18. In combination in an automatic switch, interconnected main and auxiliary contact arms, whereof the former is movably supported by the latter, a fixed contact adapted to operate as a fulcrum for the main contact arm in moving the auxiliary arm, a main electro-magnet having a moving memberfor operating the main contact arm in respect to the fixed contact and having an exciting winding, an auxiliary magnet adapted to restrain and release the movement both of the moving membercf the main magnet and of the auxiliary arm, a coil on the auxiliary magnet for releasing the moving member of the main magnet, means controlled by the auxiliary arm for modifying the excitation of the main electro-magnet, and an armature carried by the auxiliary arm and cooperating with the auxiliary magnet.

19. In combination in an automatic switch, a moving member adapted to close the switch, a magnet and its armature adapted, when suitably excited, to prevent the moving member from closing the switch, and a coil for neutralizing the excitation of said magnet to release the moving member.

20. In coml3 ination, two sources of electro-motive-force, an electro-magnetic switch for connecting them, including a moving member, electro-magnetic means for restraining the motion of the moving member to prevent the closing of the switch, and a releasing coil for said means adapted to permit the closing of the switch, said-coil connected between the two sources.

21. In an electromagnetic switch, the combination of two members adapted when brought into contact to close an electric circuit, electro-magnetic means for elfecting said contact, an clectro-magnet adapted to restrain said electro-magnetic means to prevent said contact until predetermined circuit conditions obtain and to release said means when said circuit conditions do obtain, and a device mechanically dependent upon the contact pressure between the two members and adapted to weaken the action of the electromagnetic meansafter said contact is made.

22. In an electro-magnetic switch, the combination of two members adapted when brought into contact to close an electric circuit, electro-magnetic means for efi'ecting said contact, an electro-magnet adapted to restrain said electro-magnetic means to prevent said contact until predetermined circuit Conditions obtain and to release said and the restraining magnet is efiective to 10 means when said circuit conditions do obprevent closing.

tain; a device mechanically dependent upon In testimony whereof I have hereunto the contact pressure between the twoanemsigned my name. hers and adapted to weaken the action of JOSEPH LESTER WOODBRIDGR the electr0-n1agnetic means after said contact isniade, and means for preventing the Witnesses: restoration of the electro-magneticmeans to J. H. TRACY, normal strength until the contact is open F. G. BEETEM. 

